Known rotary fuel injection systems of “fuel slingers” generally comprise an annular combustor that receives fuel fed through holes in the rotating shaft connecting the compressor and turbine. Often the fuel injection systems will employ a rotating fuel reservoir feeding the fuel to the combustion region over a circumferential lip. Examples of such fuel slinger engines are shown in U.S. Pat. No. 3,932,988 (Beaufrere), U.S. Pat. No. 4,040,251 (Heitmann et al.), U.S. Pat. No. 4,598,544 (Williams et al.), U.S. Pat. No. 4,769,996 (Barbeau), and U.S. Pat. No. 4,870,825 (Chapman).
However current small gas turbine engines suffer from poor ignition reliability due to various limitations of current combustion systems. To overcome these limitations, many combustors use pyrotechnic starting devices, which add considerable expense and weight. Additional expense is added by the use of conventional fuel nozzles, which can easily clog. Together, fuel nozzles and pyrotechnic starters can account for 40% or more of the overall cost of a small turbojet.
It is desirable therefore to provide a better combustor system and method which eliminates the need for pyrotechnics and fuel nozzles, while improving ignition reliability, reducing combustor cost, allowing for smaller, more efficient combustors, which may be especially suited for small gas turbine engines. A smaller diameter combustor is especially desirable in that it provides greater space for fan bypass. For example, in small thrust size engines (having a static thrust at sea level of 150 lbf or less) a turbofan configuration will provide better fuel consumption rates and higher thrust for a given engine diameter over a turbojet. Therefore, an improved combustor system and method applicable to turbofan engines, and in particular a small thrust turbofan, is desirable.